Vacuum



` July 10,1923.

' W. G. HOUSKEEPER VACUUM PUMP Filed June 1a, 192.1

IIIIIIIIIIII lllmfimmw/WWM .IIII Illllli l Patented July 10, 1923.

UNITED STATES PATENT OFFICE.

WILLIAM G. HOUSKEEPER, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY,` INCORPORATED, 0F NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

VACUUM PUMP.

Application filed June 16, 1921.

To all whom t may concem.'

Be it known that I, WILLIAM G. Hous- KEEPER, a citizen of the United States, re-v siding at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Vacuum Pumps, of which the following is a full, clear, concise, and exact description. This invention relates to an auxiliary pump adapted to cooperate with a roughing pump for exhausting to low pressures. It is particularly, although not exclusively useful for the production of the high vacua necessary in vacuum tubes of the pure electron discharge type.

In the application of H. C. Snoek, Serial No. 505,576, filed October 5, 1921, there is disclosed an auxiliary pump in which the pumping medium, a substance solid at room temperature and having at its melting temperature and below a vapor pressure less than that of vacuum tubes of the pure electron discharge type, is vaporized from a liquid state by means of an arc, one electrode l' of which comprises a portion of the pumping medium. In the above noted application it is proposed to use as one electrode of the arc, a member movable with respect to the puddle.

An object of this invention is to utilize a puddle of the pumping material as each electrode of the are for vaporizing the pumping'material. p

`Another object of this invention is a container for the puddles of pumping material which will not be subject to possible destruction by the expansion and contraction of the pumping material.

This invention will be betterunderstood by having reference to the following s ecification and accompanying drawing wiich is a sectional view of an embodiment of the invention. y

The vessel 1 to be evacuated is connected by means of glass tubing with a roughing pump 2, which is capable of producing a vacuum of 103 mm. of mercury. The glass tubing connecting the vessel 1 and the pump 2 comprises a vertically arranged section 3 leading to the pump and a section 4 leading from the container and entering the section ,3 at right angles thereto. The section 3 extends below the juncture of the section 4 ltherewith and carries the chamber 5 into 'which said section 3 extends. Arranged in Serial No. 478,021.

the chamber 5 is a block or container 6 of insulating material such as lavite, a commerclal form of steatite, the upper portion of which is recessed as at 7. The llower portion of the block 6 is recessed as at 8, this recess being of considerably smaller diameter than 7. The lower portion of the recess 7 1s tapered to form an annular well having a sloping bottom. In the lower portion of the block 6 and communicating with the recesses 7 and S are apertures the lower ends of which are tapped to receive the binding posts 9. Arranged in the wells or recesses 7 and 8 is the metal to be used as the pumping medium and which is in contact with the binding posts 9. Sealed in the lower end of the chamber 5 are lead wires 10 'for the binding posts 9. Surrounding the chamber and short sections of the tubes 3 and 4, is an oven 11 within which is arranged the resistance heating unit 12 which is connected in series with a source of electrical energy 13 and with the lead wires 10. A shunt 14, provided with a switch 15, is arranged around the lead wires 10. Arranged in the recess 7 and in contact with the wall thereof, is a cylindrical metallic member 16 having an arm 17 in contact with the inner end of the binding post arranged in the aperture communicating with the annular well 7.

As the pumping medium for this pump, there is used, a substance having at room temperature a vapor pressure less than the pressure within a vacuum tube of the pure electron discharge type, such for example, as lead, bismuth, tin, or the like, and the annular well is completely filled with this substance, whereas the central well iS left empty for a sho-rt distance from the top. The pumping medium is melted and the walls of the pumping chamber and the tubing heated to the melting point of said medium from the resistance units 12, the switch 15 of the shunt 14 being closed. After the pumping material has been melted, the switch 15 is opened and the device is slightly shaken to cause some of the molten metal to drop over the edge of the annular well into the central well to start thereby an electric arc between the metal in the two wells, the metal in the central well being the cathode of the arc. The heating effect of the are at the cathode is concentrated on a comparatively small portion of the metal in the central well and causes the vaporization thereof to form a vapor jet which passes through the tube 3 and entraine gas from vessel 1 in the well known manner. The vapor is condensed in the upper portion of the tube 3 and returns lin liquid form to the annular well.

After the arc has been established the element 16 becomes in effect the anode and the heat liberated at the anode is dissipated throughout the comparatively large mass thereof and does not increase the temperature in the annular well sufficient to cause vaporization therefrom. The molten metal in the aperture extending from the annular well insures good electrical contact between the arm 17 and the binding post 10.

After the pumping has been discontinued and the current shut oil from the arc, the metalin the walls contracts. The tendency of the metal in the annular well to exert pressure on its inner wall and thus cause rupture of the container, is overcome by reason of the sloping bottom provided therein. As the metal contracts, it slides up from the sloping bottom, thus preventing rupture of the container.

lVhat is claimed is:

1. In a pump, a container of insulating material, a plurality of puddles of pumping material in said container, means for heating said pumping material, and electrical connections whereby an are may be established between said puddles.

2. In a pump, a container of insulating material, a plurality of puddles of pumping material in said container, means for heating said pumping material, said puddles being connected with a source of electrical energy.

3. In a pump, a container of insulating material, a central well of pumping material, an annular well of pumping material surrounding said central well, means for heating said pumping material, and connections from said well to a source of electrical energy.

4. In a pump, a container of insulating material, a plurality of puddles of pumping material in saidv container, binding posts arranged in said container and in contact with the pumping material, and connections from said binding post to a source of electrical energy.

5. In a pump, a container having a plurality of chambers for receiving the pumping material. the bottom of one of said chambers being sloping, and means for heating said material.

6. In a pump, a container of insulating material, a plurality of puddles of pumping material in said container, a metallic member having a portion extending into one of said puddles, and connections between said puddles and a source ot electrical energy.

7. In ia pump, a Acontainer of insulating material, a plurality of puddles of pumping material in said container, a metallic member having a portion extending into one of said puddles, and connections whereby an are may be maintained between said metallic member and another of said puddles.

8. In a pump, a container of insulating material, a plurality of concentric puddles of pumping material in said container, a metallic member having a portion extending into one of said puddles, and electrical connections from said puddles to a source of electrical energy.

9. In a pump, a pumping chamber, a supply of pumping material therein,` means, for establishing an are. one electrode ot which is a portion of said supply of pumping material, means for heating the walls of said chamber comprising an electrical resistance in series with said arc.

10. In a pump, a chamber, a supply of pumping material therein, means for establishing an arc, one electrode of which is a portion of said supply of pumping material, means for heating the wall of said chamber comprising a ballast for said are.

11. In a pump, a pumping chamber, a container of insulating material supported therein, a supply of pumping material in said container, electrical means for heating said pumping material and said chamber to the melting temperature of said material. means for establishing an arc, one electrode of which is a portion of said supply of pumping material, said heating means acting as the ballast for said are.

12. In a pump, a pumping chamber, a member of insulating material having a recess, said recess being of different diameters whereby is provided a central well and an annular well. pumping material in said wells and connections between the pumping material in said wells and a source of electrical energy.

13. In a pump, a member of insulating material having a recess, said recess being of two diameters whereby is provided a cen.- tral well and an annular well, pumping material in said wells, an annular metallic member in said larger diameter portion and having an arm extending into said annular well, and connections between the pumping material in said wells and a source of elec.- trical energy.

14. In a pump, a member if insulating material having a recess, said recess being ot different diameters whereby is provided a central well and an annular well, pumping material in said wells, binding posts in said member and in contact with the pumping material in said wells, a metallic member in said larger diameter portion of the recess and having an arm extending into said annu-lar well and in contact with the binding post therefor, and connections between said binding post and a source of electrical energy.

15. In a vacuum pump, a pumping passage 'comprising a plurality of chambers for receiving a pumping material to be heated, the bottom of one of said chambers being sloping, and means for heating said material.

16. In a Vacuum pump, a pumping passage comprising an annular` chamber for receiving a pumping material to be heated, the bottom of said chamber being sloping,

y and means for heating said material.

tac-le, a container Within said receptacle,y

a liquid electrode Within said container, and means for heat-ing said liquid to produce a vapor jet.

In Witness whereof, I hereuntosub'scribe my name this 14th day of June, A. D. 1921.

WILLIAM e. HoUsKEEPER. 

